Technical Field
The present disclosure relates to a method of producing a nitride fluorescent material, a nitride fluorescent material, and a light emitting device using the same.
Description of Related Art
A light emitting device formed by combining a light emitting diode (hereinafter may be referred to as “LED”) and a fluorescent material has been increasingly applied as lighting apparatuses and backlight for liquid crystal displays, etc. For example, in the case where the light emitting device is used in a liquid crystal display device, a fluorescent material of narrow half bandwidth is desired to provide a wider range of color reproducibility.
Examples of such a fluorescent material include a red light-emitting phosphor of SrLiAl3N4:Eu (hereinafter may be referred to as a “SLAN phosphor”). For example, Patent Literature 1 (PTL1) and Non-Patent Literature 1 (NPL1) disclose SLAN phosphors having a narrow half bandwidth of 70 nm or less and having a peak fluorescence wavelength near 650 nm.
As disclosed in NPL1, a SLAN phosphor is, for example, produced such that powders of raw materials including lithium aluminum hydride (LiAlH4), aluminum nitride (AlN), strontium hydride (SrH2), and europium fluoride (EuF3) are weighed in a stoichiometric ratio so that Eu is 0.4 mol % and mixed. The mixture is placed in a crucible and calcined in a mixed gas atmosphere of hydrogen and nitrogen under atmospheric pressure at a temperature of 1000° C. for two hours.